The localized corrosion of resistant alloys in chloride solutions

A potentiostatic scratching technique has been used to study the breakdown potentials of stainless steel 304, Incoloy, Inconel 600, Monel 400 and Hastelloy C in chloride solution at pH 8 as a function of chloride activity, temperature and metal cold work. For the first four alloys breakdown occurs through pitting. For Hastelloy C there is no pitting process, and breakdown occurs by a transpassive reaction, probably involving oxidation of Mo and Cr in the film to soluble anions. † Comisión Nacional de Energía Atómica, Av. del Libertador 8250, 1429 Buenos Aires, Argentina. ‡ Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano, Italy.